Undertake titration and colorimetry to
determine the
concentration of solutions.
TITRATION
What is titration
For this assignment we as the learners had to undertake laboratory
experiments such as titration. Titration is a scientific experiment used to
determine the concentrations of solutions which are unknown. We
undertook a range of titration experiments from ; the concentration of
hydrochloric acid solution determined, the concentration of sodium
hydroxide determined, Ph titration of hydrochloric acid with sodium
hydroxide.
Calibration of equipment
Before any titration experiment can be initiated the equipment was
calibrated in order to test how accurate they were and if not replacements
could be made. By calibrating the equipment any uncertainty that could
potentially occur was reduced. Calibration of equipment included the
pipettes being used which in this case was a bulb Pipette, the balance used to
prepare the standard solution and a Ph meter.
Below I will discuss the 3 titration practicals including the method which was
undertaken, the results obtained in tabulated form including any graphs
where needed, the calculations of concentrations, the health and safety
procedures followed, percentage difference calculations and the potential
hazards and risks of the experimental procedure including the chemicals.
,Titration 1 -Determining the concentration of
hydrochloric acid solution
The purpose of the first titration experiment which we undertook was to
determine the concentration of hydrochloric acid solution by using a range of
scientific procedures and techniques. This titration consisted of 3 main parts.
Equipment list to determine the concentration of hydrochloric acid
- 50.0cm3 burette, conical flasks, water wash bottle, 25.0cm3 bulb
Pipette, 100cm3 beaker, clamp stand, white tile, funnel, bulb pipette
filer, standard sodium carbonate solution, dilute hydrochloric acid,
methyl orange indicator solution
Method
The first part to this method was to prepare the standard solution of Na2CO3.
The method for the preparation is as follows ;
- Utilsie a top pan laboratory balance and place a plastic boat onto the
balance and zero. Weigh out a certain amount of sodium carbonate.
- Once the desired amount is weighed out (1.30 g) obtain a 100cm3
beaker holding the plastic boat containing measured sodium
carbonate above and use a wash bottle to wash out the sodium
carbonate ensuring the whole amount with the water is added to the
beaker.
- Dissolve the sodium carbonate solution into the beaker by stirring this
mixture with the use of a glass rod.
- Transfer this solution from the beaker into a volumetric flask ensuring
that a funnel is attached to the top of the volumetric flask.
- To ensure that all of the sodium carbonate solution is added use a
wash bottle to wash the beaker continuously.
- Top up the volumetric flask with the water from the wash bottle until
it reaches the graduation mark with a clear Meniscus.
2
, - Use a stopper to place on the opening of the flash and invert the flask
around 7 times.
Now that the first part of the experimental procedure is completed the next
steps are to
- Clamp the burette being used into the clamp stand while checking that
the tap is closed as this will allow the leakage of the HCl acid and
interfere with results
- Place a funnel at the opening of the burette and add in hydrochloric
acid up to the zero point. Remove the funnel from the opening of the
burette and level to 0
- Using a bulb Pipette obtain 25.0cm3 of the sodium carbonate solution
prepared into a conical flask and add exactly 3 drops of indicator being
utilised which is the orange methyl indicator.
- Now record the initial volume of the hydrochloric acid contained in the
burette to 2 decimal places.
- The conical flask containing the sodium carbonate solution should be
placed underneath the burette and the tap should be opened to allow
the hydrochloric acid to be released into the conical flask.
- Once the solution turns visibility pink the tap should be closed
immediately and the remaining hydrochloric solution available in the
burette should be recorded. This method should be repeated without
the preparation of standard sodium carbonate solution 3 times
including a rough titration.
Below is a tabulated results table with the values obtained after the
completion of the method above :
Rough 1 2 3 Mean
titration
Final 28.00 28.05 28.07 28.10 28.08
burette
reading
(cm3)
3